The present invention relates to mixers for mixing audio signals and distributing the mixed audio signal (i.e., audio signal mix) and also relates to headphone amplifiers for delivering audio signals to headphones.
As well known, the mixers are means for mixing audio signals supplied from a plurality of sound sources. Today, the mixers are used widely in a variety of applications and come in various types to meet various demands.
FIG. 7 is a diagram illustrating an example of a relatively inexpensive portable-type mixer. This mixer is capable of mixing audio signals, such as those of tones performed on a musical instrument, for up to n channels and thereby generating stereophonic audio signals of left and right channels having desired sound image localization and stereo balance. Thus, with the mixer, it is possible to record audio signals generated from an ensemble performance by a plurality of human players or audibly reproduce, through one or more speakers, tones obtained from an ensemble performance. Generally, in executing an ensemble performance using a mixer, the players tend to worry about whether the ensemble performance is progressing as desired and want to directly check ensemble-performance tones produced via the mixer rather than those reproduced through the speakers. Where the mixer has an output terminal for connection with headphones, the ensemble-performance tones produced via the mixer can be checked through the headphones by just connecting the headphones to the output terminal. However, because the portable mixer, such as shown in FIG. 7, normally has only one headphone output terminal, it allows only one player to use the headphones.
Therefore, to allow all the players to monitor the ensemble performance using headphones, it is necessary to provide a distributor means that gives out the audio signals through the headphone output terminal to the individual sets of the headphones. As a typical example of the distributor means, a headphone amplifier as illustrated in FIG. 8 is often used in combination with the mixer. By the combined use of the mixer and headphone amplifier, each of the players can directly check the mixed ensemble-performance tone to thereby ascertain whether the ensemble performance is progressing in a desired manner as a whole. However, it may not be sufficient to check the ensemble performance as a whole, and each of the players might still want to know whether his or her own performance is being executed as desired. Thus, there has been a demand for a facility to allow each of the players to check his or her own performance in addition to the mixed ensemble-performance tone.
One possible approach to meed such a demand is to provide a separate mixer for each of the players as illustrated in FIG. 9. In the example of FIG. 9, mixers M1 to Mn are provided in corresponding or linked relation to the individual players. The headphone output terminal of the mixer M1 is connected with headphones of a first player, the headphone output terminal of the mixer M2 is connected with headphones of the second player, and similarly the headphone output terminal of the mixer Mn is connected with headphones of the nth player. Each of the mixers M1 to Mn mixes audio signals of first to nth channels generated by performances of the first to nth players. To allow each of the players to check his or own performance on a musical instrument, it is only necessary for each of the mixers to mix the audio signals of the individual channels with such weights that the audio signals of the corresponding channel are emphasized over those of the other channels. Namely, the mixer M1 associated with the first player executes the mixing after increasing the volume level of the audio signals of the first channel obtained from performance by the first player, the mixer M2 associated with the second player executes the mixing after increasing the volume level of the audio signals of the second channel obtained from performance by the second player, and so on. Similar technique is disclosed in Japanese Utility Model Publication No. 63-6782.
With the conventional technique illustrated in FIG. 9 or disclosed in the publication, each of the players can monitor or listen to his or her own solo performance with increased volume, against the background of the mixed ensemble-performance tone with lower volume, to ascertain whether the solo performance is being executed as desired. However, the conventionally-known technique is very uneconomical in that it requires a separate mixer for each of the players although ensemble-performance tones can normally be obtained through audio signal mixing using only one mixer.
It is therefore an object of the present invention to provide a mixer and a headphone amplifier which can fulfil the above-mentioned demand and yet are economical and simple in construction.
According to an aspect of the present invention, there is provided a mixer device which comprises: a first mixing circuit that mixes audio signals received via a plurality of input channels and thereby outputs a resultant mixed audio signal; and a second mixing circuit that individually mixes each of the audio signals received via the input channels and the mixed audio signal output by the first mixing circuit and thereby provides a mixed output signal for each of the channels, the second mixing circuit being capable of separately adjusting a mixing level of each of the audio signals received via the input channels.
If the audio signals received via the individual input channels are each called a xe2x80x9csolo-performance signalxe2x80x9d, the mixed audio signal output by the first mixing circuit combining together these received audio signals may be called an xe2x80x9censemble-performance signalxe2x80x9d. Of course, the first mixing circuit can adjustably mix the received audio signals at separately-set mixing levels, using volume controls. The second mixing circuit receives the mixed audio signal, i.e., ensemble-performance signal and individually mixes it with each of the audio signals, i.e., solo-performance signal received via the input channels. In this way, the audio signal or solo-performance signal, received by any one of the input channels, can be mixed with the ensemble-performance signal. If a player performing a given musical instrument inputs an audio signal of his or her performance tone through a particular one of the input channels and listens, via headphones or the like, to a signal produced from mixing of the thus-received or input audio signal (solo-performance signal) and the ensemble-performance signal at suitably adjusted levels, the player can catch or recognize his or her own performance and other""s performance in combined form and raise or lower the volume of his or her own performance on the musical instrument, which would prove very convenient. Besides, because the mixing of all the audio signals received via the input channels is executed by the first mixing circuit, only one such mixing circuit is sufficient, which would significantly simplify the construction of the mixer device.
According to another aspect of the present invention, there is provided a mixer device which comprises: a first mixing circuit that distributes audio signals received via a plurality of input channels respectively to a plurality of reproducing channels and mixes the audio signals, received via the input channels, in each of the reproducing channels, to thereby output mixed audio signals through the individual reproducing channels, the first mixing circuit being capable of, for each of the input channels, adjusting a mixing level of the audio signal and a distribution level ratio of the audio signal to the individual reproducing channels; and a second mixing circuit that, for each of the audio signals received via the input channels, mixes the audio signal and the mixed audio signal output by the first mixing circuit and thereby provides a mixed output signal for each of the input channels and for each of the reproducing channels, the second mixing circuit being capable of separately adjusting a mixing level of each of the audio signal received via the input channels.
The plurality of reproducing channels are left and right channels intended for stereophonic reproduction or sound image localization, and the first mixing circuit is capable of, for each of the input channels, adjusting a mixing level of the audio signal and a volume level ratio of the audio signal to be distributed to the individual reproducing channels. Thus, the audio signals can be mixed in such a manner to have unique sound image localization and stereo reproduction ratio for each of the input channels. Further, for the audio signal (solo-performance signal) received via a particular one of the input channels, the second mixing circuit mixes the received audio signal with the mixed audio signal (ensemble-performance signal) of each of the reproducing channels output from the first mixing circuit, to thereby provide a mixed output signal for each of the reproducing channels corresponding to the particular input channel. In this case, the solo-performance signal to be mixed with the ensemble-performance signal is controlled only in its mixing level and no control is executed on its sound image localization, so that a player""s solo performance can be recognized with centrally-localized sound image while the ensemble performance is recognized with unique sound image localization. As a result, the present invention achieves the mixing with realism.
According to still another aspect of the present invention, there is provided an amplifier device for use with a headphone, which comprises: a first input terminal that receives a first audio signal from an external source; a first output terminal that provides the first audio signal, received via the first input terminal, to outside the amplifier device; a second input terminal that receives a second audio signal from an external source; a mixing circuit that mixes the first and second audio signals received via the first and second input terminals, the mixing circuit including an operator for adjusting mixing levels of the first and second audio signals; and a second output terminal that supplies an output from the mixing circuit to the headphone. For example, if a performance output signal from a given player""s musical instrument is fed to the first input terminal and the first output terminal is connected to an input of an audio mixer device, the performance output signal from the player""s musical instrument can be mixed with a performance output signal from another player""s musical instrument. Then, the second input terminal is connected to an output of the audio mixer device, so that a mixed output signal (ensemble-performance signal) from the audio mixer device is received as the second audio signal. In this way, the mixing circuit mixes the signal of the given player""s own performance with the ensemble-performance signal, and the mixed result can be recognized via the headphone. Because the mixing to provide the ensemble-performance signal is executed by the external audio mixer device, the circuitry arrangement of the headphone amplifier can be simplified to a significant degree.